Lectrosonics M175DC - Manual (Page 3)

Belt Pack Transmitter
Table of Contents
General Description ............................................................................................................................................................................... 3
Controls and Functions ......................................................................................................................................................................... 4
Mic Jack ................................................................................................................................................................................................ 4
Power ON/OFF ..................................................................................................................................................................................... 4
Battery Indicator Lamp ......................................................................................................................................................................... 4
Mic Level Adjust ................................................................................................................................................................................... 4
Audio Switch ......................................................................................................................................................................................... 4
Operating Instructions .......................................................................................................................................................................... 5
Troubleshooting ..................................................................................................................................................................................... 6
Specifications and Features ................................................................................................................................................................. 6
Service and Repair ................................................................................................................................................................................. 7
Returning Units for Repair .................................................................................................................................................................... 7
General Description
Thank you for selecting the M175 Wireless Microphone
Transmitter. The M175 Series transmitters operate on
high band frequencies from 150 MHz to 216 MHz. It is
offered in three different versions to meet your specific
needs. This manual covers all versions.
Only the M175 series transmitters are covered in this
manual. Receivers are covered in separate manuals.
All versions of the M175 Series transmitters will operate
with any Lectrosonics high band VHF receiver. A
frequency matched transmitter/receiver combination
makes up a “wireless system.”
If you are new to wireless microphones, you will dis­
cover a new freedom of movement and level of conve­
nience. If you are an experienced wireless user, you
will be pleased with the versatility and superior perfor­
mance of the M175 design.
The M175 Series transmitter is offered in three ver­
sions. The standard model is the M175. The M175-LS
has an additional audio mute switch on the front panel,
and the M175DC has a proprietary Digital Code
Squelch* circuit to eliminate squelching problems
caused by interference.
The digital code system provides much more reliable
control over the receiver audio output than a conven­
tional squelch can provide. The transmitter generates
an 8-bit code at turn on, and another code at turn off, to
open and close the audio output on the receiver. The
squelch on the receiver cannot be opened by anything
other than the specific code it is programmed to receive.
This type of squelch system is even more important
when the receiver is connected into an automatic
mixing system.
The M175 transmitter uses the microphone cord for the
antenna. This feature eliminates the need for the
“dangling wire” antenna found on many transmitters.
The M175 Series transmitters use a crystal controlled
oscillator and temperature compensation circuitry to
ensure that the transmitter does not drift over time or
with age.
To suppress audible noise, a “compandor” noise
reduction circuit is used which is compatible with all
Lectrosonics 170 series, 175 series, and 185 series
receivers. In addition, the input limiting circuit will
handle >25dB of overload without distortion. The audio
circuitry is extremely quiet, with low distortion for natural
reproduction of either voice or music. The wide input
adjustment range of M175 Series transmitters allows
the use of virtually any microphone. The M175 can even
be used with modest line level inputs such as tape
recorders or musical instruments.
The M175 Series transmitters operate from a replace­
able standard 9 Volt alkaline battery. A precision
battery test circuit continuously monitors the battery
voltage. A highly visible LED glows as long as the
battery voltage is high enough to operate the transmit­
ter. A 9 Volt alkaline battery will provide up to 15 hours
of operation.
The electret microphone input jack provides 5 Volts DC
positive bias for all Lectrosonics’ electret microphones.
Many other electret microphones may be adapted to
the M175 Series by making simple wiring changes in
the microphone connector.
*DCS (Digital Code Squelch) systems require a match
between transmitter and receiver of both frequency and digital
code.
M175 Series transmitters are FCC type accepted under the
following Parts:
Part 90 (150-172 MHz), Part 74 (174-216 MHz)
Rio Rancho, NM 3